Arthrosis

Glenohumeral arthrosis has been a well-described complication of various surgical procedures to correct shoulder instability. Over-tightening of the anterior structures, can result in stiffness, and drive the humeral head posteriorly, creating shear on the cartilage and early arthrosis.

Some patients paradoxically may have instability and stiffness. They feel unstable because of excessive laxity in the axillary pouch and an untreated IGHL detachment, yet they are stiff because the MGHL, the rotator interval, and sometimes subscapularis are excessively tight. Complex releases with revision capsular shift may be required.

An example might be Z-plasty subscapularis lengthening combined with an anterior-inferior selective capsular shift. Fortunately, such scenarios are rare.

Other causes of premature osteoarthrosis are iatrogenic, such as anterior impingement from a coracoid bone block that is placed too far laterally along the glenoid rim, impingement on local hardware such as a screw, or incorrect intra-articular placement of metal anchors.